Caliper rule



April 14, 1970 H. MEYER CALIPER RULE Filed Oct. 31, 1968 United States Patent 3,505,741 CALIPER RULE Hans Meyer, 24 Bugnon, Renens, Vaud, Switzerland Filed Oct. 31, 1968, Ser. No. 772,202 Claims priority, application Switzerland, Dec. 12, 1967, 17 ,384/ 67 Int. Cl. G011) 3/20 US. Cl. 33-143 4 Claims ABSTRACT OF THE DISCLOSURE A slider mounted on wheels rolls along the beam, the wheels being adjustable to permit perfect matching of the two caliper jaws. A clamp locks the slider without exerting pressure on the wheels.

The invention relates to a caliper rule, or slide calipers, having a beam, two jaws, and a slider.

Calipers of this sort have a fixed jaw incorporated by the beam, and a movable jaw that forms part of the slider. The accuracy of measurement, aside from the precision of the graduations, depends to a very large extent on the free movement of the slider. Two rather incompatible conditions must be fulfilled: one, the slider must move as easily and uniformly as possible along the beam, so that it has the required responsiveness; and, two, there should be no play of any kind between the slider and the beam, whereby to ensure that the caliper jaws remain parallel when measurements are taken. It is extremely difificult to manufacture beams to close tolerances necessary for parallel upper and lower slide edges, and equally ditficult to produce a suitable slider that moves easily and without play. In accordance with the prior art, an attempt to solve this problem consists in a nonadjustable contact between only one surface of the slider and the beam, whereas a resilient Wedge is incorporated between the other beam sliding surface and the slider, for the purpose of adjusting the play and sliding resistance within certain limits. This scheme does improve the manufacturing requirements, but only at the cost of accurate measurement. The play between the slider and the beam can be avoided; but the wedge must press with some force on the beam, causing an additional and undesired friction, which makes the calipers more difficult to use and the slider less responsive to the touch. Thus, the two requirements-playless movement and easy adjustability of the sliderremain mutually exclusive.

The purpose of the invention is to provide a caliper rule that combines these two requirements.

An object of the invention is to provide a caliper rule, of which the slider moves on wheel means along the beam, two wheels being rigidly supported by the slider to roll along one longitudinal edge of the beam, the other wheel being resiliently supported and rolling on the other longitudinal edge of the beam while causing the rigidly supported wheels to be pressed against their associated beam edge.

This object and others of the invention will be apparent from the following detailed disclosure.

The invention will be described, with reference to the figures of the accompanying drawing, wherein:

FIG. 1 is a side view of the calipers of the invention;

FIG. 2 is a view in section taken along line B-B of FIG. 1, on a slightly expanded scale;

FIG. 3 is a view in section taken along line CC of FIG. 1, on a slightly expanded scale; and

FIG. 4 is a view in section taken along line AA of FIG. 1, on a slightly expanded scale.

With reference to the figures, the caliper rule, or slide calipers, includes a beam 1 with a fixed jaw and "ice graduations 1a, and a slider composed of a case 2, incorporating a movable jaw 2a, and cover plates 3 and 4, which are mounted on the case 2 by screws 12. Two rigidly supported wheels -5 and a resiliently supported wheel 6 are mounted in the slider. The manner in which the wheels 5 are constructed and supported is shown in FIG. 2. An axle 7, having an eccentric central part 7a, upon which a wheel 5 turns, is held in screws 8. The vertical position of these wheels can be changed by rotating the axle 7, and their lateral positions varied by turning the screws 8. In this way, the position of the slider can be so adjusted with respect to the beam so that the two jaws correctly meet.

FIGS. 1, 2, and 4 show how the wheel 6 is resiliently mounted. A pin 9 passes through the wheel and is held at either end in a flexible rocker 10, which is supported by a pin 17 held in screws 18. The right end of the rocker 10 has a flare portion 10a that eliminates all play between the rocker, on the one hand, and the case 2 and the cover plate 3, on the other. The lateral position of the wheel can be adjusted by turning the screws 18. The right end of the rocker (as seen in FIGS. 1 and 4) is resilient and pressed down by a screw 11, whereby the wheel 6 is also pressed down, so that the two wheels 5 are raised and pressed against the beam 1. The wheels 5 and 6 run along sloping guide edges 1b (see FIG. 2) embodied in the upper and lower edges of the beam 1, these guide edges being provided along the rims of grooves 1c and therefore less likely to be damaged from the outside.

Since the slider rolls on the beam, it is, for the same downward pressure, far easier to move than is the case with a slider that slides along the beam, enabling more precise measurements to be made, because the slider is far more responsive to the touch. The rolling resistance is dependent, of course, on how the wheels 5 and 6 are mounted. Consequently, a favorable ratio will be chosen between the wheel diameter and the diameter of the axle 7 or the pin 9. For extremely demanding applications, the wheels can be provided with ball bearings.

As shown in FIG. 1, the resiliently supported wheel 6 is spaced a distance a and b from the respective wheels 5. In order to ensure the greatest possible conuter moment to act against the moment that occurs when measurements are made, the distance b should be greater than a.

With caliper rules of the prior art, the locking mechanism presses the slider against one of the upper or lower guide surfaces of the beam; whereas in the calipers of the invention, the slider is locked in position by turning a clamping screw 16, causing no additional pressure on the wheels 5. The clamping force is obtained from two jaws 14 and 15, which press on the sides of the beam 1, as shown in FIGS. 3 and 4. A leaf spring 13, fixed on the case 2 by rivets 20, is pressed against the beam 1, when the slider is locked, thus preventing relative movement between the beam and the case. In addition, the clamping mechanism is freely supported in the case 2, so that it cannot cause any undesired side forces.

The guide edges 1b can be easily safeguarded against dirt by inserting, for example, seals 19.

What is claimed is:

1. A caliper rule comprising a beam having upper and lower longitudinal edges, a fixed jaw on said beam, a slider movable along said beam, a jaw on said slider constituting a movable jaw, wheel means carried by said slider and upon which said slider moves along said beam, said wheel means including two rigidly supported wheels that roll along one of said beam edges and a third wheel that rolls on the other of said beam edges, and resilient means supporting said third wheel for free rotation at a location intermediate the other wheels and urging the third wheel against the associated beam edge for causing said two rigidly supported wheels to be pressed against their associated beam edge.

2. A caliper rule as claimed in claim 1, wherein said resilient means comprises a resilient rocker mounted in said slider and supporting said third wheel, and means for tensioning said rocker so that said third wheel is resiliently pressed against its associated beam edge.

3. A caliper rule as claimed in claim 2, including means for laterally adjusting the position of said rocker with respect to said slider.

4. A caliper rule as claimed in claim 1, comprising clamping means mounted in said slider for releasably locking said slider in a desired position along said beam without causing said wheel means to be additionally pressed against said beam, said clamping means comprising a pairof clamping jaws located loosely inthe slider, a clamping screw for locking said clamping jaws and a resilient element fixed to the slider and clamped between one of the clamping jaws and the beam.

References Cited UNITED STATES PATENTS 876,162 1/1908 Flood 33143 2,795,858 6/1957 Ratzkin 33-l99 FOREIGN PATENTS 618,547 2/1949 Great Britain.

258,594 12/1967 Austria.

LEONARD FORMAN, Primary Examiner C. E. PHILLIPS, Assistant Examiner 

